The present invention related to molds and more particularly to an improved apparatus and method for stripping a molded U-shaped article from the mold.
Generally, molded U-shaped articles are formed by using an injection molding machine which comprises a molding unit and an injection unit. The molding unit has a frame on which a mold is mounted and a hydraulic apparatus for opening and closing the mold. The injection unit fluidizes plastic material and injects the fluidized plastic material into the mold.
The mold typically comprises two mold plates. One mold plate houses a plurality of cup molds while the other mold plate has an equal plurality of mandrels which are registered for a respective cup mold. When the mold is closed, one mandrel fits inside one cup mold and a closed cavity is formed. The closed cavity defines the shape of the molded U-shaped article.
Conventionally, a molded U-shaped article is formed by injecting plastic material into the closed cavity of the mold and allowing the plastic material to solidify. The hardened molded article is then removed from the mold by opening the mold.
Typically, the molded U-shaped article is intended to stick on the mandrel when the mold is opened and an ejector is used to push the molded article off of the mandrel once the molded article clears the cup mold. The molded article falls away from the mold due to gravity.
A problem associated with this type of injection molding machine is that the molded article often sticks in the cup mold. When the molded article sticks in the cup mold, either the machine is stopped and an operator physically removes the article or the supply of fluidized plastic material is cut off from that cavity and eventually, when enough cavities become blocked, the machine is shut down and an operator physically removes the stuck articles.
A solution to the sticking problem has been to coat the cup mold with a chemical compound such as a conventional mold release agent. Although this release agent does help, it eventually wears off and the molded articles stick.